Emerging fan-out packages require advances in mold compounds, polymer interfaces to metals and silicon, and innovative processing to reach the required high reliability. In this paper, we discuss the fracture energy for mold compound interface to copper and silicon, and use that information for studying interfacial delamination propagation of mold compound. We have examined mold compound delamination from silicon die as well as redistribution layer in a fan-out package, and compared the results against a lead-frame package as well as a plastic ball grid array package of similar dimensions.